The flavor of brewed beverages such as coffee and tea has long been a selling point of those who market these drinks. Both coffee and tea are complex substances containing numerous ingredients. Coffee, for example, has over 300 identified ingredients. A chief ingredient is a stimulent in the form of caffeine and tannic acid. Various aromatic oils, nitrogeneous substances, dextrins, gums and other substances supply flavor. Caffeine and flavors are extracted when ground roasted coffee beans or dried tea leaves are brewed with hot water.
Just how much flavor is extracted from ground coffee or tea leaves is a function of time, water amount and temperature, surface area and solubility. The quality of the brewing water and kind and grade of coffee or tea are also important.
When brewing coffee, the ground coffee is generally placed in a filter and hot water is added and allowed to percolate through the filter along with the dissolved coffee solids. The lightening of the color of the water coming through the filter is often taken as an indication of when all the flavor has been extracted. However, this is not the case and many flavoring agents are thrown away with spent coffee grounds. These flavoring agents of coffee are colorless or of less intense color when extracted during a brewing process. Since the public has come to expect a certain color from brewed coffee, these lighter colored and more difficulty extracted materials are not utilized.
The caffeine, acids and darker oils are extracted first during the brewing process and contribute to the bitterness or strong flavor which develops in brewed coffee upon standing for a period of time. If all the flavor ingredients were to be extracted from the brewing process, one could obtain better flavor, less bitterness and caffeine per unit of ground coffee, but at some sacrifice to the deep rich coffee color. It has been proposed that this probelm could be overcome by adding a coloring agent such as caramel powder to the ground coffee to provide color. This may work to a point, but there are other matters to be considered.
It has been said that there are three factors which need to be considered in brewing premium coffee, i.e., the grade or blend of coffee, the brewing process and the quality of water.
It has long been known that soft water is less palatable than spring or mountain water for drinking purposes. Mineral waters from special springs are shipped all over the world because of their taste and, in some cases, alleged medicinal properties. Most mineral waters contain calcium, magnesium and iron along with other ingredients including sodium, potassium, silicon, boron, fluorine and many other trace ingredients. These waters are so varied in solids content that, except for the above mentioned minerals, they are impossible to categorize.
In most cases, these mineral waters are formed by rain water seeping underground through inorganic materials such as rock and sand dissolving mineral matter along the way. Other springs rise deep from the earth, are often hot and contain gaseous materials such as sulfur. Most of the calcium magnesium, iron and other multiply charged cations in spring water are present with bicarbonates, sulfates or similar anions.
When spring water is heated for brewing coffee, many of the minerals are lost. Bicarbonates, for example, release carbon dioxide upon heating and precipitate as insoluble carbonates. Some mineral sulfates, such as calcium sulfates, are somewhat less soluble in hot water than in cold. Sulfates of transition metals, such as irons, may be oxidized when heated with the metal going from the ferrous to the ferric state, the sulfate ion being converted to a sulfur oxide which combines with water to form sulfuric acid. The ferric ion combined with oxygen to form the insoluble ferric oxide Fe.sub.2 O.sub.3.H.sub.2 O.
Due to the demineralization of water upon heating many of the desirable taste properties found in spring water are lost during the brewing process. Also, the softening of water wherein the calcium and magnesium ions are replaced with sodium makes water less palatable and flat tasting.